The present disclosure is directed towards metallic ink such as copper. Metal conductors on printed circuit boards (PCB) and flex tape connectors are generally copper (Cu) lines that are either laminated onto the PCBs or are deposited by electroplating techniques. Patterning the copper material to form conducting lines, wire and connecting leads between components requires photolithography and acid etching of blanket copper films. Alternatively, such methods can be used to define copper line patterns during the plating process. In either case, the chemicals used to etch the copper and the resultant chemical waste generated from the processes add significant cost to the products that are made. The cost is further increased due to the time and labor necessary for the etching and photopatterning process steps.
An alternative technique to lamination and electroplating for forming metal conductors on PCB includes printing the metal lines. Silver metal based inks and pastes exist for inkjet printing, screen printing and other printing techniques. Although silver is highly conductive and can be processed at low temperatures, it is an expensive metal, making it cost prohibitive for many applications.